Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Inspection Procedure
Hand-held tester:
- Check fuel pump operation (See FUEL PUMP
).
- OK: Go to step 8 .
- NG: Go to Next Step
- Connect hand-held tester, and check operation of fuel pump relay.
PREPARATION:
- Connect the hand-held tester to the DLC3.
- Turn the ignition switch ON and push the hand-held tester main switch ON.
- Enter the following menus: DIAGNOSTICS / ENHANCED OBD II / ACTIVE TEST / FUEL PUMP / SPD.
CHECK:
Check the operation of the fuel pump relay when it is switched ON and OFF by the hand-held tester.
OK:
- Operating noise can be heard from the relay.
- OK: Go to step 4 .
- NG: Go to Next Step
- Check operation of fuel pump relay (See FUEL PUMP
).
- NG: Replace fuel pump relay.
- OK: Go to Next Step
- Check fuel pump (See FUEL PUMP
).
- NG: Repair or replace fuel pump.
- OK: Go to Next Step
- Check circuit opening relay (See CIRCUIT OPENING RELAY
).
- NG: Replace circuit opening relay.
- OK: Go to Next Step
- Check for open in harness and connector between EFI or ECD relay and fuel pump, and fuel pump and body ground (See HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
).
- NG: Repair or replace harness or connector.
- OK: Go to Next Step
- Check voltage between terminal FC and E1 of ECM connector.
PREPARATION:
Turn the ignition switch ON.
CHECK:
Measure the voltage between terminal FC of the ECM connector and body ground.
OK:
- Voltage: 9 to 14 V
- NG: Check for open in harness and connector between battery and FC terminal of ECM (See HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS ).
- OK: Proceed to problem symptoms table (See PROBLEM SYMPTOMS TABLE ).
- Check fuel pump resistor (See INSPECTION
).
- NG: Replace fuel pump resistor.
- OK: Check for open in harness and connector between circuit opening relay and fuel pump resistor, and fuel pump resistor and fuel pump (See HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS ).
OBD II scan tool (excluding hand-held tester):
- Check operation of fuel pump (See FUEL PUMP
).
- OK: Go to step 7 .
- NG: Go to Next Step
- Check operation of fuel pump relay (See FUEL PUMP
).
- NG: Replace fuel pump relay.
- OK: Go to Next Step
- Check fuel pump (See FUEL PUMP
).
- NG: Repair or replace fuel pump.
- OK: Go to Next Step
- Check circuit opening relay (See CIRCUIT OPENING RELAY
).
- NG: Replace circuit opening relay.
- OK: Go to Next Step
- Check for open in harness and connector between EFI or ECD relay and fuel pump, and fuel pump and body ground (See HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
).
- NG: Repair or replace harness or connector.
- OK: Go to Next Step
- Check voltage between terminal FC of ECM connector and body ground.
PREPARATION:
Turn the ignition switch ON.
CHECK:
Measure the voltage between terminal FC of the ECM connector and body ground.
OK:
- Voltage: 9 to 14 V
- NG: Check for open in harness and connector between battery and FC terminal of ECM (See HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS ).
- OK: Proceed to problem symptoms table (See PROBLEM SYMPTOMS TABLE ).
- Check fuel pump resistor (See FUEL PUMP RESISTOR
).
- NG: Replace fuel pump resistor.
- OK: Check for open in harness and connector between circuit opening relay and fuel pump resistor, fuel pump resistor and fuel pump (See HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS ).
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
